SAE Update - March 2022 - 30

ENGINEERING EVENTS
Can U.S. cars get cleaner?
applications. A " 300/8 " design
refers to cell density of 300 cells
per square inch and wall
thickness of 8 mils.
Commercially available filters
already offer high filtration
efficiency. Even higher filtration
products are being developed to
meet upcoming Euro 7 standards,
which will cover extreme realworld
driving conditions and
include particles down to 10 nm.
The new filters will have novel
hierarchical pore structures,
which promise very high filtration
efficiencies in the fresh and clean
state, without any soot or ash.
An increase in filtration is
typically associated with an
increase in pressure drop, but
using this technology, the
additional filtration comes with
little pressure drop penalty. In
fact, with some soot
accumulation, the new GPFs
offer lower pressure drop. Unlike
engines and catalysts, the
performance of filters only
improves with mileage.
There are other benefits to
adding a GPF to an emissions
control system. Analyses of soot
particles have shown the
presence of adsorbed
carcinogenic polyaromatic
hydrocarbons (PAHs), products
30 March 2022
of incomplete combustion. Catalyzed GPFs have been
shown to remove >99% of these PAHs. Also, soot
particles are composed in large parts (>75%) of black
carbon, which is a greenhouse gas agent with 3,200
times higher global warming potential than CO2
. The
filters therefore help reduce the climate change
impact of tailpipe emissions.
Policymakers across the world are looking to
transition fleets to zero tailpipe emitting electric
vehicles, so it's fair to ask whether we should invest in
additional technologies for internal combustion
engines (ICEs). It should be noted that in the U.S.
alone, ~15 million vehicles are sold each year, with
battery electric vehicles representing only 3% of that
market. Assuming all vehicles sold are electric by
2035, calculations show that GPFs can help avoid
almost 30,000 tons of particulate emissions in the
next two decades. This suggests the need to adopt a
pragmatic approach, adding the best available, costeffective,
and proven technologies to make ICE fleets
as clean as possible.
Modern ICE vehicles can reach near-zero levels of
emissions if equipped with advanced emissions control
technologies. In fact, on-road measurements show that
the tailpipe particulate emissions for vehicles with
filters can be lower than the ambient concentrations of
highly polluted cities. In some places, the exhaust
coming out of your car is cleaner than the air around it
- and to me, that sounds like progress! n
Ameya Joshi, Ph.D., wrote this article for Update.
He is director, Emerging Technologies &
Regulations, Environmental Technologies, Corning
Inc. Joshi is a 15-year SAE member. He is scheduled
to present a technical paper/keynote on April 5 at
the WCX 2022 conference. The title of his paper is
" Review of Vehicle Engine Efficiency and Emission
Control Regulations and Technologies. " He also is
co-organizer of a WCX technical session,
" Advances in Particulate Filter Substrates. "
UPDATE
https://www.sae.org/publications/technical-papers/content/2022-01-0540/?utm_source=AP&utm_campaign=sem https://www.sae.org/publications/technical-papers/content/2022-01-0540/?utm_source=AP&utm_campaign=sem
SAE Update - March 2022

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